JSON ObjectMapper readValue解析中的差异-有时会给出Null

Question

我在使用ObjectMaper的readValue（）解析json字符串时遇到了一个奇怪的情况。我正在使用Jackson 2.4.1和Spring 4.0.6。问题是，当提供给readValue（）时，相同的json字符串有时为null，有时为有效对象
JSON字符串:

{"productGroupInfoTransport":    {"groupId":36,"range":"LMEURSMA","productType":"LMFE","status":"ANNOUNCE","regionsList":[],"productsList":[],"groupName":"Bright Start test"}}

代码：

public Object getData(String jSONObject, String action, String module)
        throws Exception {
    ObjectMapper mapper = new ObjectMapper();
    mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
    mapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES,
            false); 
    mapper.configure(DeserializationFeature.FAIL_ON_NULL_FOR_PRIMITIVES,
            false); 
    mapper.configure(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT,
            false); 
    //mapper.configure(SerializationConfig.   WRITE_NULL_PROPERTIES, false);
    String transport = null;
    if (jSONObject.contains(ERROR)) {
        transport = "Exception";
        throw new Exception("Unable to read Data");
    } else {
        transport = getTransport(action, module);
    }
    Object transportObject = null;
    transportObject = mapper.readValue(jSONObject, getTransport(transport));
    return transportObject;
}

产品运输：

package com.leggmason.lmEPAM.transport;
import java.util.List;
import com.fasterxml.jackson.annotation.JsonProperty;
import com.leggmason.lmEPAM.model.ProductGroupModel;
public class ProductGroupTransport extends EPAMTransport<ProductGroupModel> {
@JsonProperty("productGroupInfoTransport")
protected ProductGroupModel modelObject;
@JsonProperty("productGroupTransport")
protected List<ProductGroupModel> data;
@JsonProperty("productGroupTransport")
@Override
public List<ProductGroupModel> getListData() {
    return this.data;
}
@JsonProperty("productGroupTransport")
@Override
public void setData(List<ProductGroupModel> data) {
    this.data = (List<ProductGroupModel>) data;
}
@Override
public String getModule() {
    return null;
}
@JsonProperty("productGroupInfoTransport")
@Override
public ProductGroupModel getObject() {
    return this.modelObject;
}
@JsonProperty("productGroupInfoTransport")
public void setObject(ProductGroupModel modelObject) {
    this.modelObject = modelObject;
}
@Override
public void setObject(Object modelObject) {
    // TODO Auto-generated method stub
}
}

在上面的代码中，当JsonString被传递时，有一次ProductTransposrt会用Object正确填充其modelObject，但当我重新启动服务器时，相同的JSON字符串在解析后会将modelObject指定为null。我不明白为什么。谢谢你的帮助。

Answer 1

您可以尝试以下代码来解析json对象

JSONObject obj = new JSONObject(jSONObject);
JSONArray array = obj.getJSONArray("productGroupInfoTransport");
System.out.println(array.getJSONObject(0).getString("groupId"))

现在您可以正确解析json字符串了。它可能只对解析json字符串有帮助。